This invention relates to a compact, pressurizable load coil assembly.
Loading coils find extensive use in the telephone industry. Wire pairs extending between a central office and a subscriber's telephone have substantial capacitance, resulting in a change in impedance with length. It is desirable to maintain a predetermined impedance, to assure maximum signal power transfer between the central office and the subscriber's telephone. To accomplish this, inductive load coils are connected to the wire pairs at intervals, such as at pedestal cabinets, and the like are spaced a predetermined distance apart, so that the known capacitance of the resulting predetermined length of wire pairs will be balanced by the inductance of a standard load coil.
Numerous structures for load coil assemblies are known. Basically, load coils are assembled in some compact configuration, such as is shown in U.S. Pat. No. 4,172,964, issued to Reinebach on Oct. 30, 1979, and encapsulated, in an attempt to keep moisture from affecting the load coil assembly, such as by oxidizing the metal of the inductor cores, commonly toroidal cores due to the low losses obtainable with this configuration, or damaging the insulation of the wires in the load coil assembly, or forming conductive paths between wire pairs in the load coil assembly, resulting in degraded compensation and increased cross linking and cross talk between wire pairs. However, with the passage of time, encapsulating compound absorbs moisture, which eventually deteriorates the load coil assembly.
Conventionally, telephone cables may be pressurized, and may be spliced together in an airtight manner, such as by being covered with a heat-shrinkable tubing after splicing, However, where load coils are to be connected, the end of the cable is sealed off, such as by an encapsulating compound or heat-shrinkable sleeve, and the individual wire pairs of the cable are connected to individual wires extending from the load coil assembly.